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CP BIO CH. 7 CELL MEMBRANE AND TRANSPORT REVIEW TOPICS These are topics and vocabulary terms covered in this chapter which may appear on the chapter test. See chapter guide, warm-ups, quick reviews, and text chapter 7 parts 3 and 4 Ch. 2 Enzymes –What are they? – protein catalysts Why important? – speed reactions in cells Activation energy – to start a reaction, enzymes lower it Active site and substrate – what are they? Modes of enzyme action – lock-and-key, induced fit Conditions that affect enzyme action o Temperature – warm increases rate; hot denatures protein o pH – narrow range, excess H+ or OH- break 3-D bonds o concentration of enzyme or of substrate – limiting reactant o inhibitors – slow enzyme action block active site or change molecule shape 7. 2 Cell Boundaries Cell membrane o Lipid bilayer, Fluid Mosaic Model o Phospholipid: hydrophobic and hydrophilic parts o Membrane proteins – 6 kinds, cholesterol, carbohydrate tags 7.3 Cell Transport Passive transport – no cell energy/ solute moves DOWN a concentration gradient Diffusion – Small, nonpolar (O2, CO2, H2O) o Facilitated diffusion – through a membrane transport protein Pores or channels – open passage through membrane Carriers – receive on one side of membrane, release on other Small, polar or charged (glucose, amino acids, ions, water) o Osmosis – water across a membrane Osmotic pressure - force which makes water diffuse Isotonic – same solute concentration on both sides of membrane Water moves equally in both directions Natural state for animal cells; wilted for plant cells Hypotonic – low solute concentration on one side (high water concentration) Water goes FROM hypotonic TO hypertonic If cell environment hypotonic: water goes into cells o Animal cells swell, may burst (lyse) o Plant cells turgid Hypertonic – high solute concentration on one side (low water concentration) Water goes TO hypertonic FROM hypotonic If cell environment hypertonic to cell: water goes out of cells o cytoplasm shrinks - plasmolysis o Animal cells shrink, shrivel o Plant cells – cytoplasm shrinks, but wall stays Active Transport – uses cell energy ATP o Across membranes – AGAINST the gradient Protein “pumps” push particles to where they are already more concentrated In intestine – absorb as many nutrients as possible In kidneys – remove as many wastes as possible Sodium-potassium pumps – nerve cells o Bulk Transport – large particles and cells, in vacuoles or vesicles Endocytosis – bring IN to cell Phagocytosis – ‘cell eating’ – engulf food and enclose in vacuole o Amoeba, white blood cells Pinocytosis – ‘cell drinking’ – small folds in cell membrane enclose drops of liquid o Intestine lining Exocytosis – send OUT of cell vesicle filled with substance merges with cell membrane opens outside of cell to release substance o glands that make hormones or enzymes o contractile vacuoles